1. Field of the Invention
This invention relates to an absorbent article such as, catamenial napkin, incontinent pad, catamenial pad, etc. which its wearer wears together with an undergarment (hereinafter represented by "shorts") in the narrow crotch, and more particularly to an absorbent article having a high antileakage property.
2. Description of the Prior Art
The conventional absorbent article such as a catamenial napkin basically includes a liquid permeable outer material, a liquid impermeable antileakage material, and a liquid retentive absorbent element interposed therebetween. In recent years, by developing and introducing a new material such as an absorbent polymer for the absorbent element in place of the conventional cotton-like pulp or absorbent paper, an attempt has been made to improve the absorption ability of the absorbent article. Another attempt has been made in which a liquid permeable sheet is given a liquid permeability by forming tiny perforations on a hydrophobic sheet and is placed next to a non-woven fabric as a conventional fiber aggregate. This combination is used as an outer material in order to improve the absorption ability of the absorbent article.
However, even in an absorbent article in which a new material is introduced and in which each component element has an excellent efficiency, sideward leakage still occurs frequently in actual use. For example, in a case of catamenial napkins, blood leaks sidewardly and the blood reaches the shorts, creating inconvenience for the wearer and raising doubts about whether or not the original efficiency of the absorbent article is fully exhibited. The main causes of leakage in a catamenial napkin, which occur irrespective of the original efficiency of each component element, as mentioned above, are as follows:
(1) When a wearer fixes a catamenial napkin on shorts, the position of the catamenial napkin is one-sided either rightward or leftward at the crotch portion of the shorts and there exists a part of the crotch portion which is not covered with the catamenial napkin from the begining.
(2) Even if a wearer successfully correctly fixes a catamenial napkin, i.e., in a generally center area of the shorts without being one-sided either rightward or leftward relative to the crotch portion, the catamenial napkin is frequently twisted and deformed into a rolled-up state wherein each longitudinal edge of the PG,4 catamenial napkin is overlapped with the central portion because of the wearer's physical activity or movements, and an edge portion of the crotch portion which was covered with the catamenial napkin right after it was fixed is exposed due to the rolled-up deformation.
(3) When a wearer moves, it is impossible to firmly fix a catamenial napkin to the crotch portion of shorts only by fixing means such as the adhesive which a catamenial napkin usually has, and the catamenial napkin is displaced from a predetermined position and exposes the crotch portion.
Leakage caused by the above (1) through (3) is also greatly affected by the shorts to be worn by a wearer. For example, particularly when the width of the crotch portion is wide compared with the width of the napkin, or when fit to the wearer's body is bad and loosened, leakage tends to occur comparatively easily.
Therefore, in order to solve these problems, many proposals have been made in which an absorbent article is provided with a pair of flexible flaps each extending in the width direction away from a central portion of each longitudinal edge of the absorbent article (Japanese Patent Early Laid-open Publication Nos. Sho 60-75058, Hei 1-111002, Hei 2-13455, etc.). In the case of these absorbent articles, the crotch portion of the shorts, when in use, is sandwiched between and fixed by the flaps in order to stabilize the absorbent article in the shorts, thereby improving the antileakage property.
For example, a sanitary napkin described in Japanese Patent Early Laid-open Publication No. Sho 60-75058 is designed such that in a central position of each vertical side of an absorbent article, a flexible flap formed of liquid permeable outer material and liquid impermeable antileakage material extends from each side of an absorbent element, so that the flap, in use, can be pulled out from the edge portion of the shorts and fixed to an outer side of the shorts by fixing and connecting means disposed on a rear surface of the flap, thereby stabilizing the sanitary napkin and improving the antileakage property. In this sanitary napkin, it is important, in order to have it exhibit its full antileakage property, to form an antileakage wall by placing the absorbent element in such a manner as that both sides of the absorbent element face upward when the shorts are worn. If the shorts are worn in such a state as just mentioned, leakage can be prevented to some extent. However, the following problems arise.
1 Action for pulling out the flaps from both ends of the crotch of the shorts is not necessarily stable; the sanitary napkin cannot be worn together with the shorts in a constant state; and the sanitary napkin is sometimes twisted into an irregular form from the beginning of its use to thereby cause leakage.
2 If the width of the crotch portion of the shorts is wider than the width of the absorbent element, it becomes difficult to fix the sanitary napkin itself to the shorts or otherwise it sometimes happens that the sanitary napkin cannot be firmly secured to the crotch portion because an outwardly-bent area of the crotch portion is reduced.
3 Even if the antileakage wall portion is successfully formed at each side of the absorbent element by firmly securing the pair of flaps in 2, it sometimes happens that the antileakage wall portion is twisted toward and contacted with the outer surface of the absorbent element to stain the flaps themselves with blood because the width of the antileakage wall portion of the flap is wide. Therefore, although staining of the shorts can be prevented by the flaps to some extent, it sometimes happens that the flaps themselves are stained while the wearer is moving or acting and the inner crotch portion is stained with blood by the stained flaps. This sometimes provides even greater inconvenience to the wearer.
In any case, when the conventional absorbent articles described in the above-mentioned Publications are correctly fixed to a right position of shorts, leakage mentioned in the above (1) through (3) can be prevented to some extent, but in the case of shorts having a poor fit to the wearer's body and shorts having a crotch portion which is wider in width than the width of an absorbent element, the flaps fully cover the outer surface of the absorbent article. As a result, leakage cannot necessarily be prevented effectively and the flaps are stained which, in turn, stains the inner crotch portion with blood, etc. through the stained flaps.